<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Title</title>
    <style>
        *{
            padding:0;
            margin:0;
        }
        #root{
            width: 345px;
            height: 150px;
            background: skyblue;
            margin:15px auto;
        }
    </style>
</head>
<body>
<div id="root"></div>
</body>
</html>